TFF2 and complex regional pain syndrome: A review of complex regional pain syndromes (CRPS) suggests that mediators including substance P (SP), calcitonin gene‐related peptide (CGRP), bradykinin (BK), interleukin (IL)‐1β, IL‐2, IL‐6, IL‐10, and tumor necrosis factor‐α (TNF‐α) may be altered during the acute period causing shoulder pain and other symptoms (Bruehl, 2015).